This invention relates to a method of cardiac pacing and apparatus for implementing the method and more particularly to a cardiac pacer for preventing and treating arrhythmias such as atrial tachycardia involving accelerated heartbeat rates. It is well known that premature heartbeats are a manifestation of the irritability of the heart. If untreated, the premature heartbeat may start long runs of rapid heartbeats.
Various systems have been proposed for treating arrhythmias involving increased heartbeat rates, e.g., atrial tachycardia, including the use of rate scanning as proposed in the Berkovits U.S. Pat. No. 3,698,398. The rate scanning program in these devices, however, is essentially predetermined rather than being interactive with the actual functioning of the heart. The rate scan proceeds on the assumption that capture will, at some point, be established and that the heart rate will track with the scanned rate down to the desired level. It is possible, however, that neither of these assumptions may be correct. Various other systems involving manual control have also been proposed but, as will be understood, these systems involve the availability and intervention of medically-cognizant personnel and such personnel will not be universally or instantaneously available, even in a hospital environment.
Among the several objects of the present invention may be noted the provision of cardiac pacing apparatus for treating or preventing arrhythmias involving accelerated heartbeat rates; the provision of such apparatus which is interactive with and responsive to the actual functioning of the patient's heart; the provision of such apparatus which effects capture by pacing the patient's heart using a timing which is adjusted in accordance with the last naturally occurring heartbeat; the provision of such an apparatus which is operative to re-establish capture if the natural heartbeat eludes pacemaker control during the slowdown operation; the provision of such apparatus which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.